The development of divertor modules for W7-X

Abstract

For operation within a wide range of plasma and magnetic parameters an open divertor structure of the Wendelstein 7-X stellarator (optimised HELIAS configuration with superconducting coils, main parameters: R = 5.5 m, a = 0.55 m, B = 3 T, rotational transform variable between 5/6 and 5/4) has been developed. The most critical components of the divertor are ten 3D-shaped target surfaces, located along the “helical edge” of the five-fold rotational symmetry magnetic configuration of the machine. The plasma outflow concentrates on the target areas, designed to withstand a maximum stationary heat flux of 10 MW/m2. To prevent excessive radiation losses all plasma facing components will be manufactured using low-Z materials, e.g. CFC, B4C. The paper presents the optimised design of the target plates, which takes into account the latest results of the physics, the requirements of the heating and diagnostic systems, the manufacturing costs and the mounting operations in order to build a technical reliable system.